The present invention relates generally to surgical instruments and more particularly to a combination cutting and bipolar coagulation instrument.
In surgical procedures, it is common practice to use electric currents flowing from metallic instruments to achieve coagulation of blood vessels which have been cut or ruptured as a result of the surgery. Generally, a single coagulating electrode is placed in the area to be treated, while a second electrode is connected to the patient at a position remote therefrom. This second electrode has a large surface area, and the area of contact with the patient is large in order to minimize current-induced burns. Such an apparatus is known as a monopolar electrosurgical instrument. In contrast thereto, it is also possible to place two electrodes in contact with the tissue to be coagulated, one on each side of the bleeding vessel or vessels. High frequency electric current is caused to flow between the two electrodes for a time sufficient to effectuate a localized heating which results in coagulation of the vessels. The large remote electrode is not required for the implementation of the coagulation in this latter situation. Such an apparatus is known as a bipolar electrosurgical instrument.
Great precision is required for many surgical procedures, and the surgeon often uses a single, preferred hand to operate both cutting and coagulating instruments. For example, a surgeon may first use a cutting instrument, such as a scalpel, and then exchange this instrument, when necessary, for a coagulating instrument. Prior to the present invention, the surgeon would be required to redirect his attention from the area of the incision in order to receive and prepare for the operation of the coagulation instrument. A single instrument that combined the functions of cutting and coagulating would increase a surgeon's effectiveness in essentially all surgical procedures, but of singular significance is the value of such an instrument in the area of microsurgical procedures where the surgeon views the operating field with the aid of a microscope. In the application of such procedures, an exchange of instruments is particularly distracting to the surgeon.
Several examples of monopolar and bipolar electrosurgical instruments as well as other types of combination surgical and coagulation instruments will now be briefly described to provide a background for the present invention.
1. In "Surgical Cutting Instrument Having Electrically Heated Cutting Edge," U.S. Pat. No. 3,768,482 issued to Robert F. Shaw on Oct. 30, 1973, and in "Electrically Heated Surgical Cutting Instrument," U.S. Pat. No. 3,826,263, issued to John M. Cage et al. on July 30, 1974, the inventors describe the use of instruments having electrically heated cutting edges.
2. A monopolar electrosurgical instrument which is a combination forceps and scalpel is described in "Forceps, Scalpel, and Blood Coagulating Surgical Instrument," U.S. Pat. No. 4,375,218, issued to Ernest M. DiGeronimo on Mar. 1, 1983. Coagulation is achieved by a current derived from the entire contact area of the instrument with the tissue of interest. A second electrode, which is not described, is necessary to complete the current path. A likely possibility is a large electrode located away from the region of the surgery.
3. In U.S. Pat. No. 4,273,127, "Method for Cutting and Coagulating Tissue," issued to David C. Auth et al. on June 16, 1981, the inventors teach the use of laser radiation coupled to the tissue to be simultaneously cut and coagulated by means of a scalpel-like instrument which cannot be used to pressure cut tissue.
4. A bipolar coagulating surgical instrument which can be used only for coagulating tissue is described in "Longitudinally, Side-Biting, Bipolar Coagulating, Surgical Instrument," U.S. Pat. No. 4,353,371 issued to Eric R. Cosman on Oct. 12, 1982.
5. A bipolar electrosurgical knife which utilizes high frequency electrical current passed between a plurality of closely-spaced electrodes in contact with the tissue to be simultaneously cut and coagulated is described in "Bipolar Electrosurgical Knife," U.S. Pat. No. 4,228,800 issued to Howard E. Degler, Jr. et al. on Oct. 21, 1980. As in reference 3 described hereinabove, the surgical instrument cannot be used to pressure cut tissue. A similar electrosurgical knife having only two electrodes is described in "Electro-surgical Knife," U.S. Pat. No. 4,161,950 issued to James D. Doss et al. on July 24, 1979.